This week's photo
is from Pennsylvania State University, where researcher Joseph Kiesecker
tested the role that pesticides, including atrazine, play in frog deformities.
His findings suggest that pesticides severely weaken the immune system,
making frogs much more susceptible to parasitic infection and deformities
such as can be seen in Keisecker's photo. Scientists emphasize the importance
of these findings when the threat is translated to human health.

The Natural Resources
Defense Council (NRDC) recently requested the Environmental Protection
Agency (EPA) investigate Syngenta, the world's largest manufacturer
of atrazine. NRDC claims Syngenta deliberately concealed evidence of
health threats that atrazine poses to humans. They say Syngenta found
cases of prostate cancer among workers at their Louisiana manufacturing
plant in the mid 1990's, but did not report these findings until October
2001. According to the Federal Insecticide, Fungicide and Rodenticide
Act (FIFRA), pesticide registrants are required to report any adverse
health effects to EPA. EPA is taking on the investigation of Syngenta.
In his response to NRDC, Assistant Administrator Stephen L. Johnson
said, "The agency takes seriously a registrant's responsibility
to report studies and incidents of adverse effects. We are investigating
your concerns regarding Syngenta's reporting of epidemiological and
amphibian studies."

There have been
several studies done regarding the toxicity of atrazine that is cause
for concern for human health. Keisecker's study not only linked atrazine
with weakened immune systems in frogs, but slower development and smaller
size. The levels of atrazine they tested at were below EPA-recommended
levels for safe drinking water.

Joseph Keisecker
commented, "Amphibians have become an important model system. We
have to consider that factors that influence infection rates in frogs
may also play a role in human diseases."